Sky and Telescope - August 2016 - 39

PORTAL TO TEXAS HISTORY, UNIV. OF TEXAS LIBRARIES

a pocket-sized device he called a tasimeter to measure
infrared radiation, by which he hoped to determine the
heat output of the solar corona while the body of the Sun
hid behind the Moon.
To Rawlins also went University of Michigan astronomer James Craig Watson and his wife Annette. Watson,
renowned for his many asteroid discoveries, was in the
hunt for the elusive (in fact nonexistent) planet Vulcan.
A total eclipse would provide an excellent chance to
discover this small planet supposedly circling close to
the Sun. Astronomers worldwide had been trying to ﬁnd
it, after the French astronomer Urbain J. J. Le Verrier
predicted its existence from a tiny unexplained increment
(some 43 arcseconds per century) in the rate of precession
of Mercury's perihelion. Mistaken sightings had seemed
to conﬁrm the new planet. Only in 1915 was Mercury's
drift revealed to be not a perturbation by an unseen
planet, but a result of gravity's behavior under Einstein's
general theory of relativity (S&T: Dec. 2015, p. 18).
Other prominent astronomers ﬂooding to the eclipse
path were Allegheny Observatory director and solar
astronomer Samuel Pierpont Langley, who climbed the
14,000-foot Pikes Peak to obtain the best possible views
of the corona. Princeton solar astronomer Charles Young
and visiting English barrister and amateur astronomer
Arthur C. Ranyard went to Cherry Creek, near Denver.
The U.S. Naval Observatory's George W. Hill and New
York amateur Lewis Swift set up in Denver itself. So did
Nantucket astronomer Maria Mitchell and ﬁve of her
female students. Asaph Hall, renowned for his discovery of the two satellites of Mars a year earlier, went to La
Junta in southeastern Colorado. David Peck Todd headed
for Dallas, Texas, among the southernmost sites. Many
members of the public, newspaper reporters, and amateur
astronomers came as well. A few were serious observers.
Most, like today, were tourists or accidental onlookers.
On the day of the eclipse, the skies over most locations
were wonderfully clear. The various observational programs unfolded as planned, though with mixed results.
At Rawlins, Henry Draper succeeded in photographing the spectrum of the corona. Poor Mrs. Draper was
assigned to a subservient role for the men; she was nominated timekeeper, and dutifully counted the seconds of
totality from inside a tent, "blind to the spectacle, lest the
sight of it unnerve her and cause her to lose count!"
At Rawlins strong westerly winds were nearly continuous, leading Watson to move his instruments to an
isolated Union Paciﬁc rail stop at Separation, about midway between Rawlins and Creston. He was joined there
by another late arrival, Simon Newcomb. Sheltering
their equipment in the lee of a semicircular sand dune,
they prepared to wait out the partial phases of the eclipse
in eager anticipation of the scant minutes of totality,
when they would scour the solar vicinity for Vulcan.
During the excitement of the eclipse, Watson spotted

NEAR THE ECLIPSE TRACK'S END At the S. W. Lomax
farm near Fort Worth, Texas, astronomers stand by their telescopes awaiting the eclipse and a possible glimpse of Vulcan.

NANTUCKET MARIA MITCHELL
ASSN. / THE TROUVELOT
ASTRONOMICAL DRAWINGS

SOUVENIRS Middle: Faring better than Mrs. Henry Draper, who
was consigned to a tent in Rawlins, Wyoming, the famed Nantucket
astronomer Maria Mitchell and ﬁve of her female students awaited
the eclipse at Denver. Below: This magniﬁcent - if not entirely
accurate - chromolithograph of the eclipse was made by the French
artist-astronomer Etienne Leopold Trouvelot, recording his impressions from Creston, Wyoming.

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Sky and Telescope - August 2016

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